we know that
Melinda's family has walked ---------------> 4/6 of a hiking trail
in this case the 100% of a hiking trail is 6/6
then
if 100%----------------> 6/6
X%----------------> 4/6
X=(4/6)*100/(6/6)------> 400/6------> 66.67 %
Owens family has walked ---------------> 5/8 of another trail
in this case the 100% of a trail is 8/8
then
if 100%----------------> 8/8
X%----------------> 5/8
X=(5/8)*100/(8/8)------> 500/8------> 62.5 %
therefore
66.67% > 62%
the answer is
Melinda's family